1,600 endangered frog tadpoles to be released into natural B.C. habitat

A new conservation effort at the Vancouver Aquarium aims to rejuvenate the population of B.C.'s most endangered amphibian.

More than 1,600 northern leopard frog tadpoles will be transported on a chartered plane and released in Cranbrook in southeast B.C. on June 24.

They're just some of the hundreds of thousands of the species' tadpoles that have been spawned at a special facility at the aquarium in order to restore a population that suffered mysterious die-offs in the 1980s and 1990s. 

"They're what most people think of when they think of a frog," says Vancouver Aquarium senior biologist Kris Rossing, describing the green frogs with distinctive brown spots.

But future generations in B.C. are in danger of never getting to see them in the wild. 

"The frogs have kept being on a downward spiral. They're really on their last legs in the province," Rossing said.

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Rossing said the northern leopard frog is an instrumental link in the ecosystem's food chain, being the layer between birds and mammals and small invertebrates — the frogs eat the bugs and, in turn, are eaten by the larger animals. 

"Without that link between the food chains, there's a lot missing. Those higher predators have to move on and find another food source," he explains. 

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Why has its population sunk?

Scientists have not yet conclusively proven the cause of the population plunge in the late-1980 and 1990s.

Rossing says there are some theories, but ultimately they're all guesses.

"Whatever hit them off here in B.C. did affect most of their population in Canada," he says. 

Their recovery has fared better in Ontario and the Prairies, owing to easier movement of animals between the United States and Canada. in B.C., however, the Rocky Mountains act as a barrier, restricting their wild population to Creston Valley in the Kootenay region of southeastern B.C.

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However, recovery efforts like the one at Vancouver Aquarium have been successful in introducing newly bred tadpole populations to other regions in B.C. 

In collaboration with the Northern Leopard Frog Recovery Team, Vancouver Aquarium has raised and released more than 7,100 frog tadpoles since 2013.

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